U.S. patent application number 12/552678 was filed with the patent office on 2010-09-30 for classifying method and classifying device.
This patent application is currently assigned to Fuji Xerox Co., Ltd.. Invention is credited to Hiroshi KOJIMA, Seiichi TAKAGI.
Application Number | 20100243539 12/552678 |
Document ID | / |
Family ID | 42782806 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100243539 |
Kind Code |
A1 |
KOJIMA; Hiroshi ; et
al. |
September 30, 2010 |
CLASSIFYING METHOD AND CLASSIFYING DEVICE
Abstract
A classifying device having two or more classifying passages is
provided, the classifying device including a first classifying
passage to which particle dispersion liquid is fed; plural
discharge ports provided in the first classifying passage, the
plural discharge ports including a discharge port of coarse
particle dispersion liquid and a discharge port of fine particle
dispersion liquid; a second classifying passage; and a connecting
passage that transports the coarse particle dispersion liquid to
the second classifying passage, wherein the discharge port of the
coarse particle dispersion liquid is provided in more upstream part
of the first classifying passage than the discharge port of the
fine particle dispersion liquid.
Inventors: |
KOJIMA; Hiroshi; (Kanagawa,
JP) ; TAKAGI; Seiichi; (Kanagawa, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
Fuji Xerox Co., Ltd.
Tokyo
JP
|
Family ID: |
42782806 |
Appl. No.: |
12/552678 |
Filed: |
September 2, 2009 |
Current U.S.
Class: |
209/157 ;
209/155 |
Current CPC
Class: |
B03B 5/64 20130101 |
Class at
Publication: |
209/157 ;
209/155 |
International
Class: |
B03B 5/00 20060101
B03B005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2009 |
JP |
2009-075661 |
Claims
1. A classifying device having two or more classifying passages,
the classifying device comprising: a first classifying passage to
which particle dispersion liquid is fed; a plurality of discharge
ports provided in the first classifying passage, the plurality of
discharge ports including a discharge port of coarse particle
dispersion liquid and a discharge port of fine particle dispersion
liquid; a second classifying passage; and a connecting passage that
transports the coarse particle dispersion liquid to the second
classifying passage from the discharge port of the coarse particle
dispersion liquid, wherein an average particle diameter of
particles contained in the coarse particle dispersion liquid is
larger than an average particle diameter of particles contained in
the particle dispersion liquid fed to the first classifying
passage, an average particle diameter of particles contained in the
fine particle dispersion liquid is smaller than the average
particle diameter of the particles contained in the particle
dispersion liquid fed to the first classifying passage, and the
discharge port of the coarse particle dispersion liquid is provided
in more upstream part of the first classifying passage than the
discharge port of the fine particle dispersion liquid.
2. The classifying device according to claim 1, wherein at least
one of said two or more classifying passages has an inclination
relative to a vertical direction.
3. The classifying device according to claim 1, wherein at least
one of said two or more classifying passages has the discharge port
of the coarse particle dispersion liquid, the discharge port of the
fine particle dispersion liquid and a discharge port of dilution
liquid, and a concentration of weight percentage of particles in
the dilution liquid is lower than a concentration of weight
percentage of the particles in the fine particle dispersion
liquid.
4. The classifying device according to claim 3, wherein at least
one of said two or more classifying passages has a circulating
passage, the circulating passage transporting dilution liquid to
the classifying passage having the circulating passage or other
classifying passage and circulating the dilution liquid.
5. The classifying device according to claim 1, wherein, in at
least one of said two or more classifying passages, a sectional
area of passage in a downstream part is larger than a sectional
area of the passage in an upstream part.
6. The classifying device according to claim 1, wherein the
classifying device does not include an introducing port of
transporting liquid.
7. The classifying device according to claim 1, wherein the first
classifying passage has a particle dispersion liquid introducing
port that introduces the particle dispersion liquid.
8. The classifying device according to claim 1, having two to ten
classifying passages.
9. The classifying device according to claim 1, having four to
seven classifying passages.
10. The classifying device according to claim 2, wherein an
inclination angle of the classifying passage is larger than
0.degree. and smaller than 90.degree..
11. The classifying device according to claim 2, wherein an
inclination angle of the classifying passage is larger than
15.degree. and 75.degree. or smaller than 75.degree..
12. A classifying method comprising: feeding particle dispersion
liquid to a first classifying passage of a classifying device that
includes a plurality of classifying passages; classifying particles
contained in the particle dispersion liquid while transporting the
particle dispersion liquid through the first classifying passage,
wherein a plurality of discharge ports are provided in the first
classifying passage; and transporting at least one discharge liquid
discharged from any one of the plurality of discharge ports to a
second classifying passage, wherein an average particle diameter of
particles contained in the discharge liquid transported to the
second classifying passage is larger than an average particle
diameter of the particles contained in the particle dispersion
liquid fed to the first classifying passage.
13. The classifying method according to claim 12, further
comprising: transporting discharge liquid to at least one of the
plurality of classifying passages, wherein the discharge liquid is
discharged from the first classifying passage and has a particle
concentration lower than that of the particle dispersion liquid fed
to the first classifying passage; and circulating the discharge
liquid.
14. The classifying method according to claim 12, wherein the first
classifying passage to which the particle dispersion liquid is fed
has an inclination relative to a vertical direction.
15. The classifying method according to claim 12, wherein the first
classifying passage has a discharge port of coarse particle
dispersion liquid and a discharge port of fine particle dispersion
liquid, and R.sub.A, R.sub.B and R.sub.C satisfy following formula:
R.sub.C<R.sub.A<R.sub.B wherein R.sub.A represents an average
particle diameter of particles contained in the particle dispersion
liquid fed to the first classifying passage; R.sub.B represents an
average particle diameter of particles contained in the coarse
particle dispersion liquid discharged from the discharge port of
the coarse particle dispersion liquid; and R.sub.C represents an
average particle diameter of particles contained in the fine
particle dispersion liquid discharged from the discharge port of
the fine particle dispersion liquid.
16. The classifying method according to claim 12, wherein the first
classifying passage has a particle dispersion liquid introducing
port that introduces the particle dispersion liquid.
17. The classifying method according to claim 12, wherein the
classifying device has two to ten classifying passages.
18. The classifying method according to claim 12, wherein the
classifying device has four to seven classifying passages.
19. The classifying method according to claim 14, wherein an
inclination angle of the first classifying passage is larger than
0.degree. and smaller than 90.degree..
20. The classifying method according to claim 14, wherein an
inclination angle of the first classifying passage is larger than
15.degree. and smaller than 75.degree..
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35
U.S.C. 119 from Japanese Patent Application No. 2009-075661 filed
Mar. 26, 2009.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to a classifying method and a
classifying device.
[0004] 2. Related Art
[0005] A method for classifying fine particles includes a dry
method and a wet method. Since a specific gravity difference
between a fluid and the fine particle is large in the dry method,
the dry method may be highly accurate. In the wet method, the
specific gravity difference between a liquid and the fine particle
is small, however, since the fine particles are easily dispersed in
the liquid, a high classifying accuracy is obtained for a micro
power area. The classifying device ordinarily includes a rotor of a
rotating part and a stator of a stationary part to classify the
fine particles by a balance between a centrifugal force and an
inertia force. Further, in the dry method, the classifying device
using a "Coanda effect" having no rotating part is merchandized. On
the other hand, in recent years, various kinds of methods for
carrying out a chemical reaction and a unit operation in a micro
area are have been studied and a method and a device have been
investigated for efficiently classifying the fine particles without
producing impurities.
SUMMARY
[0006] According to an aspect of the present invention, there is
provided a classifying device having two or more classifying
passages, the classifying device including:
[0007] a first classifying passage to which particle dispersion
liquid is fed;
[0008] plural discharge ports provided in the first classifying
passage, the plurality of discharge ports including a discharge
port of coarse particle dispersion liquid and a discharge port of
fine particle dispersion liquid;
[0009] a second classifying passage; and
[0010] a connecting passage that transports the coarse particle
dispersion liquid to the second classifying passage from the
discharge port of the coarse particle dispersion liquid,
[0011] wherein an average particle diameter of particles contained
in the coarse particle dispersion liquid is larger than an average
particle diameter of particles contained in the particle dispersion
liquid fed to the first classifying passage,
[0012] an average particle diameter of particles contained in the
fine particle dispersion liquid is smaller than the average
particle diameter of the particles contained in the particle
dispersion liquid fed to the first classifying passage, and the
discharge port of the coarse particle dispersion liquid is provided
in more upstream part of the first classifying passage than the
discharge port of the fine particle dispersion liquid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Exemplary embodiments of the present invention will be
described in detail based on the following figures, wherein:
[0014] FIG. 1 is a schematic sectional view showing one example of
a classifying device of an exemplary embodiment;
[0015] FIG. 2 is a schematic sectional view showing another example
of the classifying device of the exemplary embodiment;
[0016] FIGS. 3A and 3B are schematic views showing other example of
the classifying device of the exemplary embodiment;
[0017] FIGS. 4A and 4B are schematic views showing other example of
the classifying device of the exemplary embodiment;
[0018] FIGS. 5A to 5F are schematic views showing manufacturing
processes of the classifying device by a connecting method at an
ordinary temperature;
[0019] FIG. 6 is a diagram showing the collection rate of particles
of an example 1;
[0020] FIG. 7 is a diagram showing the collection rate of particles
of an example 2; and
[0021] FIG. 8 is a diagram showing a relation between a
sedimentation distance and a particle diameter.
DETAILED DESCRIPTION
[0022] A classifying device of this exemplary embodiment has two or
more classifying passages. A first classifying passage to which
particle dispersion liquid is fed has plural discharge ports. The
discharge ports provided in the first classifying passage include
the discharge ports for coarse particle dispersion liquid (refer
them also to as "coarse particle dispersion liquid discharge
ports", hereinafter) and the discharge ports for fine particle
dispersion liquid (refer them also to as "fine particle dispersion
liquid discharge ports", hereinafter). The average particle
diameter of particles included in the coarse particle dispersion
liquid is larger than the average particle diameter of particles
included in the particle dispersion liquid fed to the first
classifying passage. The average particle diameter of particles
included in the fine particle dispersion liquid is smaller than the
average particle diameter of the particles included in the particle
dispersion liquid fed to the first classifying passage. The coarse
particle dispersion liquid discharge ports are provided in more
upstream parts of the classifying passage than the fine particle
dispersion liquid discharge ports. Connecting passages are provided
for transporting the liquid to the second classifying passage from
the coarse particle dispersion liquid discharge ports.
[0023] Further, a classifying method of this exemplary embodiment
includes a process that feeds particle dispersion liquid to a first
classifying passage of a classifying device having plural
classifying passages, a process that transports the liquid in the
first classifying device and classifies particles in the particle
dispersion liquid, and a process that transports at least one of
discharged liquids discharged from plural discharge ports provided
in the first classifying device to a second classifying passage,
and is characterized in that the average particle diameter of the
particles included in the discharged liquid fed to the second
passage is larger than the average particle diameter of the
particles included in the particle dispersion liquid fed to the
first classifying passage.
[0024] According to this exemplary embodiment, even when high
concentration dispersion liquid is classified, a classifying
efficiency is excellent. Accordingly, the dispersion liquid does
not need to be prepared as dilution solution. Further, as described
below, a classifying process may be carried out without
transporting liquid.
[0025] In this exemplary embodiment, a dispersion medium of the
dispersion liquid including the particles is simply referred to as
a dispersion medium, hereinafter.
[0026] Now, referring to the drawings, the present invention will
be described in detail. Unless a special description is given, the
same reference numerals designate the same objects in the following
explanation. Further, a description of "A to B" representing a
numerical range represents "A or more and B or less" and represents
a numerical range including A and B as end points.
First Exemplary Embodiment
[0027] FIG. 1 is a schematic sectional view showing one example of
a classifying device of an exemplary embodiment.
[0028] In FIG. 1, the classifying device 100 includes four
classifying passages 101, 102, 103 and 104. The classifying
passages respectively include four coarse particle dispersion
liquid discharge ports 111a to 111d, 112a to 112d, 113a to 113d and
114a to 114d and one fine particle dispersion liquid discharge
ports 121, 122, 123 and 124.
[0029] Further, the classifying device 100 of the present exemplary
embodiment includes connecting passages 131a to 131d for
transporting liquid to the second classifying passage 102 from the
coarse particle dispersion liquid discharge ports 111a to 111d of
the first classifying passage 101. In FIG. 1, are also provided
connecting passages 132a to 132d for transporting liquid to the
third classifying passage 103 from the coarse particle dispersion
liquid discharge ports 112a to 112d of the second classifying
passage 102 and connecting passages 133a to 133d for transporting
liquid to the fourth classifying passage 104 from the coarse
particle dispersion liquid discharge ports 113a to 113d of the
third classifying passage 103.
[0030] Further, in the first classifying passage 101, a particle
dispersion liquid introducing port 141 is provided for introducing
the particle dispersion liquid.
[0031] The classifying device of the present exemplary embodiment
has two or more classifying passages. In FIG. 1, the classifying
device 100 includes the four classifying passages 101, 102, 103 and
104, however, the present exemplary embodiment is not limited
thereto and the present exemplary embodiment may include two or
more classifying passages. In order to obtain a high classifying
efficiency, the classifying device preferably includes 2 to 10
classifying passages, and more preferably include 4 to 7
classifying passages.
[0032] Plural classifying passages are provided so that particles
may be classified in multi-stages and a higher classifying
efficiency may be obtained than that by a classifying process of
one stage. The particles may not be sufficiently classified by one
stage. Namely, inhibiting the commingling of coarse particles with
the fine particle dispersion liquid discharged from the fine
particle dispersion liquid discharge ports and the improvement of a
collection rate of the fine particles may not be realized together.
Further, when the number of classifying passages is 7 or smaller,
the residence time of the particle dispersion liquid in the
classifying device is preferably short and a throughput is
desirably high.
[0033] In the present exemplary embodiment, the "classifying
efficiency" means a throughput per unit time (a classifying
capability) and/or what is called a classifying accuracy. Here, the
classifying accuracy represents what quantity of coarse powder that
is desired to be removed is included in a collected part, for
instance, when unnecessary coarse powder is removed. As the
classifying accuracy is higher, other particles than particles
having desired particle diameters are the less mixed.
[0034] In this exemplary embodiment, at least one of the
classifying passages is preferably provided to have an inclination
relative to a vertical direction. Namely, the classifying passage
preferably has an angle relative to a horizontal direction and a
vertical direction. An inclination angle of the classifying passage
is larger than 0.degree. and smaller than 90.degree.. The
inclination angle is preferably 15.degree. or larger from the
viewpoint that the particles drop along an inclined surface.
Further, the inclination angle is preferably 75.degree. or smaller
from the viewpoint of obtaining a sufficient classifying
efficiency. The inclination angle of the classifying passage is
more preferably 20.degree. or larger and 70.degree. or smaller, and
furthermore preferably 30.degree. or larger and 60.degree. or
smaller. Here, the inclination of the classifying passage means an
upward inclination of a bottom surface of the classifying passage
relative to the direction of gravity. For instance, a horizontal
passage has an inclination of 0.degree.. An inclination angle of
the upper surface of the classifying passage is not especially
limited in this exemplary embodiment. Further, all the plural
classifying passages are preferably provided to have inclinations
relative to the vertical direction.
[0035] In FIG. 1, the inclination angle of the classifying passage
is designated by .theta.. Further, in FIG. 1, all the four
classifying passages have the inclination angle .theta..
[0036] A classifying principle of the classifying device shown in
FIG. 1 will be described below.
[0037] Ordinarily, when the specific gravity of the particles is
large relative to the dispersion medium of the particle dispersion
liquid, the particles are settled at a speed proportional to the
square of the particle diameter of the particle. In the case of
homogeneous particles, the particles having large particle
diameters are rapidly settled. On the other hand, the particles
having small particle diameters are hardly settled.
[0038] In the present exemplary embodiment, in the particle
dispersion liquid, the specific gravity of the particles is larger
than the specific gravity of the dispersion medium.
[0039] In FIG. 1, the particle dispersion liquid A is fed to the
first classifying passage 101 from the particle dispersion liquid
introducing port 141. In the present exemplary embodiment, while
the particle dispersion liquid A is fed to the classifying passage,
since the particles having the large particle diameters (refer them
also to coarse particles) in the particle dispersion liquid A have
high sedimentation speed, these particles reach a bottom surface (a
lower surface in the vertical direction) 151 of the first
classifying passage 101. On the other hand, the particles having
the small particle diameters (refer them also to as fine particles)
do not reach the bottom surface 151 and are directly discharged
from the fine particle dispersion liquid discharge port 121
provided in the downstream part of the classifying passage 101.
[0040] The coarse particles reaching the bottom surface 151 of the
first classifying passage 101 are settled along the bottom surface
151 of the first classifying passage in accordance with the gravity
and fed to the second classifying passage 102 through the
connecting passages 131a to 131d from any of the coarse particle
dispersion liquid discharge ports 111a to 111d.
[0041] Here, the passage length of the classifying passage may be
selected depending on various kinds of parameters such as the
particle diameters of the desired particles, a difference between
the specific gravity of the dispersion medium of the particle
dispersion liquid introduced to the classifying device and the
specific gravity of the particles and a sectional area of the
classifying passage or the like, and is not especially limited. For
instance, when it is an object to remove the coarse particles
having a specific particle diameter or more, a sufficient distance
is provided between the coarse particle dispersion liquid discharge
ports and the fine particle dispersion liquid discharge port so
that the coarse particles are designed not to be mixed in the fine
particle dispersion liquid to be discharged. Even when the fine
particles are mixed in the bully particle dispersion liquid
discharged from the coarse particle dispersion liquid discharge
ports 111a to 111d, since the classifying device 100 includes
plural classifying passages (102 to 104), the mixed fine particles
are collected as the fine particle dispersion liquid by the
classifying passages (102 to 104) after the second classifying
passage 102. Thus, the fine particle dispersion liquid is excellent
in its collection rate and small in mixture of the coarse
particles.
[0042] Further, while the particle dispersion liquid is fed to the
second classifying passage 102, the coarse particles are settled in
the direction of gravity in the second classifying passage 102 as
in the feed of the liquid in the first classifying passage 101 and
transported to the coarse particle dispersion liquid discharge
ports 112a to 112d. On the other hand, the fine particles are fed
to the fine particle dispersion liquid discharge port 122. In FIG.
1, 152, 153 and 154 denote bottom surfaces of the second, third and
fourth classifying passages 102, 103 and 104 respectively.
[0043] In the classifying device shown in FIG. 1, the particle
dispersion liquid A is supplied from the particle dispersion liquid
introducing port 141 provided in a lower part of the classifying
device 100. An introducing method for the particle dispersion
liquid A is not especially limited and may be suitably selected
from known methods. The particle dispersion liquid A is preferably
introduced under pressure by a micro cylinder, a rotary pump, a
screw pump, a centrifugal pump, a piezo-pump or the like.
[0044] The particle dispersion liquid is preferably fed from a
lower part to an upper part from the viewpoint that the particles
included in the particle dispersion liquid are settled. To
transport the particle dispersion liquid from the lower part to the
upper part does not mean only a case that the particle dispersion
liquid is fed in a vertical direction. Assuming that the particle
dispersion liquid fed in a horizontal direction has a flow vector
of 0.degree., the particle dispersion liquid fed from the lower
part to the upper part in the vertical direction has a flow vector
of 90.degree. and the particle dispersion liquid fed from the upper
part to the lower part in the vertical direction has a flow vector
of -90.degree., to transfer the particle dispersion liquid from the
lower part to the upper part means that the flow vector is larger
than at least 0.degree. and 90.degree. or smaller. The flow vector
has the same preferable range as that of the inclination angle of
the bottom surface of the classifying passage.
[0045] In the present exemplary embodiment, the coarse particle
dispersion liquid discharge ports 111a to 111d are provided in
parts more upstream than the fine particle dispersion liquid
discharge port 121. In this exemplary embodiment, since the
particles are classified by using the sedimentation speed
difference of the particles, the discharge ports of the coarse
particle dispersion liquid (the coarse particle dispersion liquid
discharge ports) 111a to 111d including the coarse particles having
higher sedimentation speed are provided in upstream parts. The
discharge port of the fine particle dispersion liquid (the fine
particle dispersion liquid discharge port) 121 including the fine
particles having lower sedimentation speed is provided in a
downstream part.
[0046] In all the classifying passages, the coarse particle
dispersion liquid discharge ports are preferably provided in the
parts more upstream than the fine particle dispersion liquid
discharge ports. Specifically, in any of the first classifying
passage to the fourth classifying passage, the coarse particle
dispersion liquid discharge ports (111a to 111d, 112a to 112d, 113a
to 113d and 114a to 114d) are respectively provided in the upstream
parts of the fine particle dispersion liquid discharge ports (121,
122, 123 and 124).
[0047] The average particle diameter (R.sub.A) of the particle
dispersion liquid A introduced to the first classifying passage
101, the average particle diameter (R.sub.B) of the coarse particle
dispersion liquid B discharged from the coarse particle dispersion
liquid discharge ports 111a to 111d and the average particle
diameter (R.sub.C) of the fine particle dispersion liquid C
discharged from the fine particle dispersion liquid discharge port
121 satisfy a below-described relational expression.
R.sub.C<R.sub.A<R.sub.B
[0048] Here, when plural coarse particle dispersion liquid
discharge ports are provided in one classifying passage, an entire
part of the coarse particle dispersion liquids discharged from all
the coarse particle dispersion liquid discharge ports satisfies the
above-described relation. Further, when plural fine particle
dispersion liquid discharge ports are provided in one classifying
passage, an entire part of the fine particle dispersion liquids
discharged from all the fine particle dispersion liquid discharge
ports similarly satisfies the above-described relation.
[0049] In the present exemplary embodiment, the diameter of a
section of the classifying passage corresponding to a circle (the
diameter of a circle having the sectional area of the classifying
passage) is preferably 10 .mu.m to 20 cm, more preferably 100 .mu.m
to 1 cm and furthermore preferably 1 mm to 5 mm.
[0050] When the diameter of the section of the classifying passage
corresponding to the circle is located within the above-described
range, the sedimentation distance of the particles in the particle
dispersion liquid is preferably short and a time necessary for the
particles to be settled to a passage wall is drastically reduced to
increase efficiency. Further, even when a flow velocity is high, a
laminar flow may be maintained so that the deterioration of the
classifying capability due to a turbulent flow may be prevented.
Further, under the laminar flow, the flow velocity of the particles
is preferably substantially zero in a wall surface to improve the
classifying efficiency.
[0051] Here, assuming that the sectional area of the classifying
passage is A, the diameter a of the section corresponding to the
circle is given by a below-described equation.
a = 2 A .pi. ##EQU00001##
[0052] Specifically, a preferable passage size (a sectional area of
the passage, a width of the passage, etc.) is determined by a time
required for the particles to be processed are settled and reach
the bottom surface.
[0053] When the particles are processed for time t (sec), assuming
that the sedimentation speed of the particles to be processed is v
(m/s), the height h (m) of the passage is expressed by an equation
(1). When a circular pipe is used, the height h of the passage
corresponds to the diameter of a circle.
h=vt (1)
[0054] The sedimentation speed v of the particles is expressed by a
below-described equation (2) in an area of low Reynolds number in
accordance with the Stokes' equation. Here, D (cm) represents a
diameter of a particle to be processed, .rho..sub.p (g/cm.sup.3)
represents a particle density, .rho..sub.d (g/cm.sup.3) represents
a density of the dispersion medium, .mu. (g/cmsec) represents a
coefficient of viscosity of the dispersion medium and g (m/s.sup.2)
represents acceleration of gravity.
v = ( .rho. p - .rho. d ) g 18 .mu. D 2 ( 2 ) ##EQU00002##
[0055] Here, it is assumed that a processing time is desired to be
set to 10 seconds. When the dispersion medium is deionized water
(.rho..sub.d=1, .mu.=0.01), the particle density is 1.2 g/cm.sup.3
((a) in the drawing, acryl or the like), 1.5 g/cm.sup.3 ((b) in the
drawing), 2 g/cm.sup.3 ((c) in the drawing, silica or the like) and
4 g/cm.sup.3 ((d) in drawing, alumina or the like), respectively, a
relation between the height (the sedimentation distance) h and the
particle diameter D is shown in FIG. 8.
[0056] From this graph, for instance, when acrylic resin particles
having the particle diameter of about 10 .mu.m are processed, since
the sedimentation distance is about 0.1 mm (an arrow mark shown by
a dotted line in FIG. 8), the height of several tens to several
hundreds .mu.m is necessary. Further, in the case of heavy
particles such as alumina, even when the particle diameter is 10
.mu.m equal to that of the acrylic resin particles, the
sedimentation distance is about 2 mm (an arrow mark shown by a
dashed line in FIG. 8) and the height on the order of about 2 mm is
required. Further, when the particle diameter of the acrylic resin
particle is increased to a size as large as 100 .mu.m, the
sedimentation distance is 10 mm (an arrow mark shown by a full line
in FIG. 8), the height on the order of mm to cm is required.
[0057] Here, the particles are supposed to be processed in ten
seconds, however, when the particles are processed in 100 seconds
(on the order of minute), the sedimentation distance is increased
by one figure order, and the diameter of the circular pipe is also
increased by one figure order. When an ordinary processing speed is
considered, the order of 100 seconds is substantially a limit. It
is not realistic to require more processing time. As described
above, as the passage size, there are optimum sizes on the order of
several tens .mu.m to several cm depending on the specific gravity
or the size of the particle. Further, as the passage size, a
desired passage size is preferably selected in accordance with the
above-described parameters.
[0058] In this exemplary embodiment, the sectional form of the
classifying passage is not especially limited, however, a circular
form or a rectangular form is preferable from the viewpoint that
the device is easily manufactured. Further, the sectional forms of
the connecting passages and a below-described circulating passage
are not especially limited, however, a circular form or a
rectangular form is preferable from the viewpoint that the device
is easily manufactured.
[0059] In FIG. 1 and below-described FIG. 2, the first classifying
passage to the fourth classifying passage and the connecting
passages have the sections of circular forms (tubular).
[0060] The classifying passage may have the same sectional area
from the upstream part to the downstream part of the classifying
passage. In the upstream part or the downstream part of the
passage, the sectional area of the passage may be increased or
decreased and is not especially limited. The sectional area of the
passage in the downstream part is preferably larger than that of
the upstream part from the viewpoint of improvement of the
processing speed. Particularly, as described below, when a dilution
solution discharge port is provided, the sectional area of the
downstream part of the classifying passage is preferably larger
than the sectional area of the passage in the upstream part of the
classifying passage. A detail thereof will be described below.
[0061] In the present exemplary embodiment, a fluid (the particle
dispersion liquid) in the classifying passage is fed in a laminar
flow.
[0062] Since, under the laminar flow, the speed of the particles is
substantially zero in the vicinity of the wall surface, the
particles colliding with the bottom surface drop along the inclined
surface due to the gravity, and are discharged from the discharge
ports provided in the classifying passage.
[0063] The classifying passage is, as described above, preferably
provided to have an inclination relative to the vertical direction.
In other words, the classifying device of this exemplary embodiment
preferably includes a classifying process that allows the
dispersion liquid to pass the classifying passage having the
inclination relative to the vertical direction and classifies the
particles.
[0064] In the present exemplary embodiment, the particle dispersion
liquid fed in the classifying passage preferably has the Reynolds
number of 1,000 or smaller. The Reynolds number is more preferably
1.times.10.sup.-5 to 100 and furthermore preferably
1.times.10.sup.-5 to 10.
[0065] Particularly, when the Reynolds number is 2,300 or smaller,
the fluid fed in the classifying passage is governed not by the
turbulent flow, but by the laminar flow.
[0066] Since a micro passage has a micro scale, a dimension (a
representative length) is small. Thus, even when the flow velocity
is high, the Reynolds number is 2,300 or smaller. Accordingly, the
classifying device having the passage of the micro scale is not
governed by the turbulent flow as in an ordinary rector, but by the
laminar flow.
[0067] Here, the Reynolds number (Re) is obtained in such a way as
described below. When the Reynolds number is 2,300 or smaller, the
classifying device is governed by the laminar flow.
[0068] The Reynolds number (Re) is proportional to the flow
velocity (u(m/s) and the representative length (L(m)).
Re = uL v ( 3 ) ##EQU00003##
[0069] Here, .nu. represents a coefficient of kinematic viscosity
(m.sup.2/c) of the fluid. When the passage has a rectangular
section, the representative length (L (m)) is prescribed by a
below-described equation.
L = 4 S l p ( 4 ) ##EQU00004##
[0070] Here, S represents a sectional area (m.sup.2) and l.sub.p
represents the length of a periphery (m). Assuming that the width
of the rectangular section of the passage is x (m) and the height
is h (m), a below-described equation (5) is established.
S=hx l.sub.p=2(x+h) (5)
[0071] Assuming that the flow rate of the fluid is a (m.sup.3/s), a
below-described equation (6) is established.
u = a S ( 6 ) ##EQU00005##
[0072] When the equation (4), the equation (5) and the equation (6)
are substituted for the equation (3), a below-described equation
(7) is derived.
Re = 2 a v 1 x + h ( 7 ) ##EQU00006##
[0073] Here, the deionized water is supposed to be fed to the
passage having a rectangular form at a prescribed flow velocity
(for instance, 10 ml/h) The coefficient of kinematic viscosity of
the deionized water at 25.degree. C. is 0.893.times.10.sup.-7
m.sup.2/s.
[0074] When the height h of the passage is constant and the width x
of the passage is a variable, the Reynolds number is inversely
proportional to the width of the passage.
[0075] In such a way, the passage in which the Reynolds number is
2,300 or smaller may be designed. When the height h is sufficiently
small, even if the width x of the passage is increased, the laminar
flow may be maintained.
[0076] A preferred form of the present exemplary embodiment will be
more specifically described below.
[0077] When the particles having desired particle diameters or
smaller are collected from the dispersion liquid, if the dispersion
liquid is fed in the classifying passage from the lower part to the
upper part in the direction opposite to the direction of gravity
(this maybe occasionally expressed by a "upward flow") the
particles whose terminal speed is lower than the speed of the
upward flow ride on the upward flow and are fed to the upper part
of the classifying passage. On the other hand, the particles whose
terminal speed is higher than the speed of the upward flow are
settled in the direction of gravity. In the upper part of the
classifying passage, a discharge passage is provided so that the
particles having prescribed particle diameters or smaller may be
collected. Further, in the lower part of the classifying passage, a
discharge passage is provided so that the particles having
prescribed particle diameters or smaller may be collected. Further,
the classifying passage has the inclination relative to the
direction of gravity, so that the speed of the upward flow may be
lowered and the particles may be efficiently classified.
[0078] The classifying device and the classifying method of the
present exemplary embodiments classify the particles in the
dispersion liquid by using the classifying passages and employing
the difference of the sedimentation speed of the particles. In the
present exemplary embodiment, the dispersion liquid needs to be
essentially fed in a laminar flow in all the classifying passages
and is preferably supplied in the flows in all the classifying
passages.
[0079] In the present exemplary embodiment, when the bottom surface
of the classifying passage has the inclination, the particles that
come into contact with the inclined surface due to the
sedimentation are settled along the bottom surface of the
classifying passage, that is, the inclined wall surface. As
described above, since, under, the laminar flow, the flow velocity
of the particles is substantially zero in the wall surface, when
the dispersion liquid fed to the classifying passage is governed by
the laminar flow, the particles in contact with the bottom surface
of the classifying passage hardly receive the influence of the
upward flow and are settled in accordance with the gravity
depending on the difference of the specific gravity from that of
the dispersion medium. Accordingly, the particles may be classified
in a shorter length of the passage than that of a usual
sedimentation classifying device and the particles may be
classified in a shorter time.
[0080] When the specific gravity of the particles is higher than
that of the dispersion medium, the particles are settled. The
sedimentation speed at that time is different depending on the
specific gravity of the particles or the particle diameter. In the
present exemplary embodiment, the particles are classified by using
the difference of the sedimentation speed. When the particle
diameters are different, the sedimentation speed is proportional to
the square of the particle diameter. The particles having the large
particle diameters are the more quickly settled.
[0081] In the present exemplary embodiment, not only the difference
of the sedimentation speed is used, but also an external force
proportional to the particle diameter of the particle is applied to
the particles so that the width of the particle to which the
classifying method may be applied is increased. As such an external
force, an electric field or a magnetic field may be
exemplified.
<Substitute Fluid>
[0082] When the particles are settled, since the fluid flows into a
position where the particles have been so far, a microscopic upward
flow arises. This phenomenon is called a boycott effect that causes
the particles to be agitated even under the laminar flow and the
classifying efficiency to be deteriorated. Thus, especially, under
a high concentration (5 wt % or higher), the classifying
efficiently is extremely deteriorated.
[0083] As compared therewith, in the classifying device of the
present exemplary embodiment, since the particles are separated
under the upward flow, the influence of the boycott is suppressed
so that the separation of the particles may be highly efficiently
carried out.
<Particle>
[0084] In the present exemplary embodiment, the size of the
particles to be classified is not especially limited, however, the
particle diameter of the particle (a diameter or a maximum particle
diameter) is preferably 0.1 .mu.m or larger and 1,000 .mu.m or
smaller. The classifying device and the classifying method of the
present exemplary embodiment are more preferably suitable for
classifying the particles of the particle diameter of 1 .mu.m or
larger and 100 .mu.m or smaller, and furthermore preferably
suitable for classifying the particles of the particle diameter of
5 .mu.m or larger and 20 .mu.m or smaller.
[0085] When the particle diameter of the particles is 1,000 .mu.m
or smaller, the occurrence of the clogging of the passage may be
preferably suppressed. On the other hand, when the particle
diameter of the particles is 0.1 .mu.m or larger, the particles
preferably hardly adhere to the wall surface.
[0086] The kinds of the particles to be classified are not
especially limited. Resin fine particles, inorganic fine particles,
metal fine particles, ceramic fine particles, cells (for instance,
lymph, leucocyte, erythrocyte or the like) may be exemplified
without a special limitation. Further, a biological sample (all
blood) or a suitably diluted biological sample may be used as
dispersion liquid.
[0087] Further, polymer fine particles, crystals or aggregates of
an organic material such as a pigment, crystals or aggregates of an
inorganic material, fine particles of metal compounds such as metal
oxide, metal nitride, etc. and toner particles may be
classified.
[0088] Further, forms of the particles are not especially limited
and any of spherical forms, rotary elliptic forms, monolithic
forms, pin-shaped forms or the like may be employed. Since the
passage is hardly clogged by the particles of the spherical forms
or the rotary elliptic forms among them, the particles preferably
have the spherical forms and/or the rotary elliptic forms. The
ratio of the length of a major axis to the length of a minor axis
(the length of the major axis/the length of the minor axis) is
preferably 1 or larger and 50 or lower, and more preferably 1 or
larger and 20 or smaller.
[0089] As the polymer fine particles, may be specifically
exemplified the fine particles of a polyvinyl butyral resin, a
polyvinyl acetal resin, a polyallylate resin, a polycarbonate
resin, a polyester resin, a phenoxy resin, a polyvinyl chloride
resin, a polyvinylidene chloride resin, a polyvinyl acetate resin,
a polystyrene resin, an acryl resin, a methacryl resin, a
styrene-acryl resin, a styrene-methacryl resin, a polyacryl amide
resin, polyamide resin, a polyvinyl pyridine resin, a cellulose
resin, a polyurethane resin, an epoxy resin, a silicone resin, a
polyvinyl alcohol resin, casein, a vinyl chloride-vinyl acetate
copolymer, a modified vinyl chloride-vinyl acetate copolymer, a
vinyl chloride-vinyl acetate-maleic anhydride copolymer, a
styrene-butadinene copolymer, a vinylidene chloride-acrylonitrile
copolymer, a styrene-alkyd resin, a phenol-formaldehyde resin,
etc.
[0090] Further, as the fine particles of metal or the metal
compounds, may be exemplified the fine particles of metal such as
carbon black, zinc, alumina, copper, iron, nickel, chromium,
titanium, etc. or alloys of them, metal oxides such as TiO.sub.2,
SnO.sub.2, Sb.sub.2O.sub.3, In.sub.2O.sub.3, ZnO, MgO, iron oxide
or compounds of them, metal nitride such as silicon nitride or
combinations thereof.
[0091] The fine particles are produced by many methods. In most of
cases, the fine particles are produced in a medium liquid (the
dispersion medium) by a synthesis and the fine particles are
directly classified. The fine particles produced by mechanically
cracking a massive material may be occasionally dispersed in the
medium liquid to be classified. In this case, the massive material
is frequently cracked in the medium liquid (the dispersion medium)
and directly classified.
[0092] On the other hand, when a power material (the fine
particles) produced by the dry method is classified, the powder
material needs to be previously dispersed in the medium liquid. As
a method for dispersing the dry powder material in the medium
liquid, may be exemplified a sand mill, a colloid mill, an
attritor, a ball mill, a diner mill, a high pressure homogenizer,
an ultrasonic disperser, a cobble mill, a roll mill, etc. At this
time, the powder material is preferably dispersed in the medium
liquid under a condition that primary particles are not ground by
the dispersion.
<Dispersion Medium>
[0093] As the dispersion medium of the particle dispersion liquid
including the particles, any solvent may be used without special
limitation, however, the solvent is used whose specific gravity is
smaller than that of at least one kind of the particles in the
dispersion liquid. The solvent is preferably used whose specific
gravity is smaller than those of all the particles in the
dispersion liquid.
[0094] A difference obtained by subtracting the specific gravity of
the dispersion medium or the transporting liquid from the specific
gravity of the particle is preferably respectively 0.01 or larger.
A specific gravity difference is preferably large so that the
sedimentation speed of the particles is high. However, the specific
gravity difference is preferably 20 or smaller. The specific
gravity difference is more preferably 0.05 to 11 and further more
preferably 0.05 to 4. When the difference obtained by subtracting
the specific gravity of the dispersion medium or the transporting
liquid from the specific gravity of the particle is 0.01 or larger,
the particles are preferably settled. On the other hand, when the
difference is 20 or smaller, the sedimentation speed is preferably
proper so that the clogging hardly occurs.
[0095] As the dispersion medium and the transporting liquid, the
dispersion liquid and the transporting liquid in which the
difference obtained by subtracting the specific gravity of the
dispersion medium from the specific gravity of the particle is 0.01
to 20 may be preferably used as described above. For instance,
water, aqueous medium, an organic solvent medium or the like may be
exemplified.
[0096] As the water, may be exemplified ion exchanged water,
distilled water, electrolytic ion water or the like. Further, as
the organic solvent medium, may be specifically exemplified
methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl
cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone,
cyclohexanone, methyl acetate, n-butyl acetate, dioxane,
tetrahydrofuran, methylene chloride, chloroform, chlorobenzene,
toluene, xylene, etc. and mixtures of two or more kinds of
them.
[0097] In the present exemplary embodiment, a preferable dispersion
medium is different depending on the kinds of the particles to be
classified. As the preferable dispersion medium for each kind of
the particles, may be preferably exemplified an aqueous medium that
does not dissolve the particles, organic solvents such as alcohol,
xylene, etc., acidic or alkaline water or the like as the
dispersion medium combined with polymer particles (ordinarily, the
specific gravity is about 1.05 to 1.6).
[0098] Further, as the dispersion medium combined with the
particles of the metal or the metal compounds (ordinarily, the
specific gravity is about 2 to 10), may be preferably exemplified
water that does not damage the metal by oxidization or reduction,
organic solvents such as alcohol, xylene, etc., or oil.
[0099] In the present exemplary embodiment, preferably, the
classifying passage does not have a transporting liquid introducing
port. Here, the transporting liquid indicates a solvent including
no particles and fed to the classifying passage.
[0100] The transporting liquid is used so that a quantity of the
fluid fed to the classifying passage is increased. Thus, since a
throughput per unit time is lowered, it is preferable in the
exemplary embodiment that the transport is not fed.
[0101] In the classifying device 100 shown in FIG. 1, the section
of each of the classifying passages 101 to 104 is circular and a
diameter thereof is 5 mm. The length of the classifying passage is
150 mm. Further, the diameters of the fine particle dispersion
liquid discharge port and the coarse particle dispersion liquid
discharge port are 1 mm.
[0102] In the first exemplary embodiment, the specific gravity of
the particles included in the dispersion liquid, the diameter of
the particle, the specific gravity of the dispersion medium and the
transfer speed of the dispersion liquid are suitably selected so
that the particles of desired particle diameters may be classified.
Further, when the length of the classifying passage is larger, the
classifying capability is the more increased. However, when the
length of the classifying passage is lengthened, a volume required
for the classifying device is increased. Accordingly, the length of
the classifying passage is preferably suitably selected depending
on a purpose.
Second Exemplary Embodiment
[0103] FIG. 2 is a schematic sectional view showing another
preferred example of the present exemplary embodiment. This
exemplary embodiment is different from the first exemplary
embodiment shown in FIG. 1 with respect to three points described
below. [0104] (1) The sectional area of a passage is increased in a
downstream part of a classifying passage. [0105] (2) In the
downstream part of the classifying passage, a discharge port of
dilution liquid is provided as well as a fine particle dispersion
liquid discharge port. [0106] (3) A circulating passage is provided
for transporting the liquid to other classifying passage from the
discharge port of the dilution liquid.
[0107] In a classifying device 100 shown in FIG. 2, in a first
classifying passage 101 to a fourth classifying passage 104, coarse
particle dispersion liquid discharge ports (111a to 111d, 112a to
112d, 113a to 113d and 114a to 114d) and fine particle dispersion
liquid discharge ports (121, 122, 123 and 124) are provided as in
FIG. 1. In the first classifying passage 101 to the third
classifying passage 103, the sectional areas of the passages are
increased in the downstream parts.
[0108] When the classifying passage has its section more increased
in an advancing direction of dispersion liquid, below-described
advantages are obtained. Namely, when the transport speed of the
dispersion liquid is low, since a dispersion liquid introducing
passage and/or the classifying passage is occasionally clogged with
particles, the transport speed of the dispersion liquid needs to be
set to such a speed not to generate a clogging. On the other hand,
when the transport speed of the dispersion liquid is too high, the
transport speed exceeds the terminal speed of the particles, and
accordingly, the particles may not be sufficiently classified.
[0109] When the sectional area of the classifying passage is
increased relative to the advancing direction of the dispersion
liquid, as the dispersion liquid is fed to a more downstream part,
a flow velocity is the lower. Accordingly, even when the transport
speed of the dispersion liquid is increased in an upstream part,
the particles may be sufficiently classified and a classifying
efficiency may be improved by suppressing the clogging.
[0110] Further, in the downstream part of the classifying passage,
the discharge port of the dilution liquid (express it as a
"dilution liquid discharge port", hereinafter) 161 is provided as
well as the fine particle dispersion liquid discharge port 121. The
dilution liquid discharge port is preferably provided in an upper
surface (an upper part in a vertical direction) of the classifying
passage.
[0111] The concentration (wt %) of the particles included in the
dilution liquid discharged from the dilution liquid discharge port
161 is preferably lower than the concentration (wt %) of the
particles of fine particle dispersion liquid discharged from the
fine particle dispersion liquid discharge port 121. A lower
concentration of the particles that are included in the dilution
liquid is the more preferable. From the viewpoint that the dilution
liquid is fed to the circulating passage and fed to the second
classifying passage, a diameter of the dilution liquid discharge
port and a position where the dilution liquid discharge port is
proved may be suitably selected.
[0112] In FIG. 2, the first classifying passage 101 further has a
circulating passage 171 for transporting the dilution liquid to the
second classifying passage 102.
[0113] The present exemplary embodiment is not limited to a form in
which the dilution liquid discharged from the first classifying
passage 101 is fed to the second classifying passage 102. The
dilution liquid discharged from the first classifying passage 101
may be fed to the first classifying passage 101, and may be fed to
the third classifying passage 103 or the fourth classifying passage
104. From the viewpoint that the concentration of the particles of
the particle dispersion liquid fed to the classifying passage is
properly maintained among them, the dilution liquid discharged from
the first classifying passage is preferably fed to the second
classifying passage. Similarly, the dilution liquid discharged from
the second classifying passage 102 is preferably fed to the third
classifying passage 103 through a circulating passage 172. The
dilution liquid discharged from the third classifying passage 103
is preferably fed to the fourth classifying passage 104 through a
circulating passage 173.
[0114] Further, in FIG. 2, in the fourth classifying passage 104, a
dilution liquid discharge port and a dilution liquid circulating
passage are not provided, however, a circulating passage may be
provided for transporting the dilution liquid to the first
classifying passage 101 from the fourth classifying passage 104. In
this case, since a throughput per unit time is lowered as an entire
part of the classifying device, a processing capability per unit
time is not preferably deteriorated, for instance, by increasing
the concentration of the particles of the particle dispersion
liquid fed to the first classifying passage.
[0115] The classifying device having the circulating passage will
be described in more detail.
[0116] In the exemplary embodiment, the fine particle dispersion
liquid discharged from the fine particle dispersion liquid
discharge port 121 is preferably provided in a sufficiently
downstream part in order to prevent the particles (coarse
particles) having desired particle diameters or larger from being
mixed. In this case, when a quantity of the fine particle
dispersion liquid discharged from the fine particle dispersion
liquid discharge port 121 is considered, the concentration of the
particles of coarse particle dispersion liquid fed to the second
classifying passage 102 may be occasionally higher than that of the
particle dispersion liquid A fed to the first classifying passage
101.
[0117] When the concentration of the particles of the particle
dispersion liquid fed to the classifying passage and a connecting
passage is high, an interaction between the particles may arise to
lower a classifying efficiency. Further, the classifying passage
and the connecting passage may be occasionally clogged with the
particles. Accordingly, it is preferable to prevent the
concentration of the particles in the particle dispersion from
being excessively high. In the present exemplary embodiment, since
the dilution liquid is fed to the second classifying passage
through the circulating passage, the concentration of the particles
in the particle dispersion liquid fed to the second classifying
passage is lowered. As a result, the classifying efficiency is
preferably improved. In FIG. 2 132 and 163 denote discharge ports
of the dilution liquid of second and third classifying passages 102
and 103, respectively.
Third Exemplary Embodiment
[0118] FIGS. 3A and 3B are schematic views showing other preferred
example of the classifying device of the present exemplary
embodiment. FIG. 3A is a perspective view and FIG. 3B is a
sectional view taken along a line X-X' of FIG. 3A.
[0119] In FIGS. 3A and 3B, a coarse particle dispersion liquid
discharge port 111 of a first classifying passage 101 is provided
in a slit form in a bottom surface side in a vertical direction of
the classifying passage 101 having a circular section. Further, a
connecting passage 131 transports coarse particle dispersion liquid
to a second classifying passage 102 from the discharge port
111.
[0120] As shown in FIGS. 3A and 3B, the coarse particle dispersion
liquid discharge port of the slit form is provided so that the
discharge efficiency of the coarse particle dispersion liquid is
preferably improved and a pressure difference from the first
classifying passage 101 to a fourth classifying passage 104 may be
preferably decreased.
[0121] In FIGS. 3A and 3B, the length of the classifying passage,
the sectional area of the passage, the width of the slit, the
length of the slit or the like may be suitably selected in
accordance with a desired particle size, a liquid transport speed
determined from the difference of specific gravity between a
dispersion medium and particles, the viscosity of the dispersion
medium, etc. When toner particles having the particle diameters of
1 to 50 .mu.m are fed by using water as the dispersion medium, a
ratio (L:M) of the diameter of a section of the classifying passage
(L in FIG. 3B) to the width of the slit (M in FIG. 3B) is
preferably set to 5:1 or so.
Fourth Exemplary Embodiment
[0122] FIGS. 4A and 4B are schematic views showing other preferred
example of the classifying device of the present exemplary
embodiment. FIG. 4A is a perspective view and FIG. 4B is a
sectional view taken along a line X-X' of FIG. 4A.
[0123] The classifying device 100 shown in FIGS. 4A and 4B is the
same as the classifying device 100 shown in FIGS. 3A and 3B except
that sectional forms of classifying passages 101, 102, 103 and 104
are different from those of the classifying device shown in FIGS.
3A and 3B.
[0124] In FIGS. 4A and 4B, the sectional form of the classifying
passage is rectangular, and more specifically square, and an
angular part is arranged so as to be directed downward.
[0125] The section is rectangular as shown in FIGS. 4A and 4B, so
that coarse particle dispersion liquid may be more easily fed to a
bully particle dispersion liquid discharge port and a classifying
efficiency is preferably excellent.
(Method for Manufacturing Classifying Device)
[0126] Now, a method for manufacturing the classifying device of
the present exemplary embodiment will be described below.
[0127] The classifying device of the present exemplary embodiment
may be manufactured on a solid substrate by a micro machining
technique.
[0128] As an example of a material used as the solid substrate,
metal, Teflon (a registered trademark), glass, ceramics and
plastic, etc. may be exemplified. Metal, silicon, Teflon (the
registered trademark), glass and ceramics are preferable among them
from the viewpoints of a heat resistance, a pressure resistance, a
solvent resistance and a light transmission. The glass is
especially preferable.
[0129] The micro machining technique for manufacturing a passage is
described in, for instance, "Micro reactor--Synthesizing technique
of new age--" (2003, published C.M.C, supervised by Junichi
Yoshida), "Micro machining technology, Application
edition--Application to Photonics.Electronics.Mechatronics) (2003,
published by N. T. S., Learned society of polymer (edited by event
committee) or the like.
[0130] As representative methods, may be exemplified an LIGA
technique using an X-ray lithography, a high aspect ratio
photolithography method using EPON SU-8, a micro discharge
machining method (.mu.-EDM), a high aspect ratio machining method
of slicon by Deep RIE, a Hot Emboss machining method, an optical
molding method, a laser machining method, an ion beam machining
method and a mechanical micro cutting work method using a micro
tool made of a hard material such as diamond. These techniques may
be independently employed or may be combined together to be used.
Preferable micro machining techniques are the LIGA technique using
the X-ray lithography, the high aspect ratio photolithography
method using EPON SU-8, the micro discharge machining method
(.mu.-EDM) and the mechanical micro cutting work method.
[0131] The passage used in the present exemplary embodiment may be
manufactured in such a way that a pattern formed by using a
photo-resist on a silicon wafer is employed as a mold and the mold
is filled with a resin to solidity the resin (a molding method). In
the molding method, a silicon resin such as polydimethyl siloxane
(PDMS) or derivatives thereof may be used.
[0132] Further, in the present exemplary embodiment, when the
classifying device is produced, a connecting technique maybe used.
An ordinary connecting technique is roughly classified into a
solid-phase connection and a liquid-phase connection. In an
ordinarily used connecting method, as the solid-phase connection, a
connection under pressure method or a diffused connection method
may be exemplified. As the liquid-phase connection, a welding
method, a soldering method, a bonding method or the like may be
exemplified as representative connecting methods.
[0133] Further, in the connection, a highly accurate connecting
method is desirable which maintains a dimensional accuracy without
the generation of a damage of a micro structural body such as the
passage due to the decomposition or deformation of the material
under heating at high temperature. As a technique thereof, may be
exemplified a direct connection of silicon, an anode connection, a
surface activating connection, a direct connection using a hydrogen
bond, a connection using HFS aqueous solution, an Au--Si eutectic
connection, a void free connection, a diffused connection or the
like.
[0134] Since the passage of the classifying device of the present
exemplary embodiment has a three-dimensional form, the classifying
device is preferably formed by laminating pattern members (thin
film pattern members). The thickness of the pattern member is 5 to
50 .mu.m, and more preferably 10 to 30 .mu.m.
[0135] The classifying device of the present exemplary embodiment
is preferably formed by laminating the pattern members on which
prescribed two-dimensional patterns are formed. The pattern members
are preferably laminated under a state that the surfaces of the
pattern members come into direct contact with each other and are
connected together.
[0136] Plural pattern members respectively corresponding to
sectional forms in the horizontal direction of the classifying
device is preferably laminated to form the classifying device so
that the classifying device may be simply formed.
[0137] As a preferred method for manufacturing the classifying
device of the present exemplary embodiment, a method for
manufacturing the classifying device may be exemplified that
includes (i) a process for forming plural pattern members
respectively corresponding to the sectional forms of a desired
classifying device on a first substrate (a donor substrate
manufacturing process) and (ii) a process for transferring the
plural pattern members on the first substrate to a second substrate
by repeating a connection and a separation of the first substrate
on which the plural pattern members are formed and the second
substrate (a connecting process).
[0138] The method for manufacturing the classifying device of the
present exemplary embodiment will be more specifically
described.
[Donor Substrate Manufacturing Process]
[0139] In the present exemplary embodiment, a donor substrate is
preferably manufactured by using an electro-casting method. Here,
the donor substrate indicates a substrate that the plural pattern
members respectively corresponding to the sectional forms of the
desired classifying device are formed on the first substrate. The
first substrate is preferably formed with ceramics or silicon and
metal such as stainless steel may be preferably suitably used.
[0140] Initially, the first substrate is prepared. A thick film
photo-resist is applied to the first substrate and exposed by
photo-masks respectively corresponding to the sectional forms of
the classifying device to be manufactured, and the photo-resist is
developed to form a resist pattern in which positives and negatives
of the sectional forms are respectively inverted. Then, the
substrate having the resist pattern is immersed in a plating bath
to allow, for instance, nickel plating to grow on the surface of
the metal substrate that is not covered with the photo-resist. The
pattern members are preferably formed with copper or nickel by
using the electro-casting method.
[0141] Then, the resist pattern is removed to form the pattern
members respectively corresponding to the sectional forms of the
classifying device on the first substrate.
(Connecting Process)
[0142] The connecting process is a process for transferring the
plural pattern members on the donor substrate to a target substrate
by repeating the connection and the separation of the first
substrate (the donor substrate) on which the plural pattern members
are formed and the second substrate (the target substrate) The
connecting process is preferably carried out by a connection at
ordinary temperature or a surface activating connection.
[0143] FIGS. 5A to 5F show a production process diagram
illustrating one exemplary embodiment of a manufacturing method of
the classifying device preferably employed in a third exemplary
embodiment.
[0144] As shown in FIG. 5A, on a donor substrate 405, plural
pattern members (401A and 401B) respectively corresponding to the
sectional forms of a desired classifying device is formed on a
metal substrate 400 as a first substrate. The donor substrate 405
is arranged in a lower stage in a vacuum bath not shown in the
drawing and a target substrate 410 is arranged in an upper stage in
the vacuum bath not shown in the drawing. Subsequently, the vacuum
bath is exhausted to have a high vacuum state or a super-high
vacuum state. Then, the lower stage is moved relative to the upper
stage to locate the pattern member 401A of a first layer of the
donor substrate 405 immediately below the target substrate 410.
Then, the surface of the target substrate 410 and the surface of
the pattern member 401A of the first layer are irradiated with an
argon atomic beam to clean the surfaces.
[0145] Then, as shown in FIG. 5B, the upper stage is lowered to
press the target substrate 410 and the donor substrate 405 under a
prescribed load force (for instance, 10 kgf/cm.sup.2) for a
prescribed time (for instance, 5 minutes). Thus, the target
substrate 410 is connected to the pattern member 401A of the first
layer at ordinary temperature (the surface activating connection).
In this exemplary embodiment, the pattern members are laminated in
order of the pattern members 401A, 401B, . . . .
[0146] Then, as shown in FIG. 5C, when the upper stage is lifted to
separate the donor substrate 405 from the target substrate 410, the
pattern member 401A of the first layer is peeled off from the metal
substrate (the first substrate) 400 and transferred to the target
substrate 410 side. This phenomenon occurs, because the adherence
force of the pattern member 401A to the target substrate 410 is
larger than the adherence force of the pattern member 410A to the
metal substrate (the first substrate) 400.
[0147] Then, as shown in FIG. 5D, the lower stage is moved to
locate the pattern member 401B of a second layer of the donor
substrate 405 immediately below the target substrate 410. Then, the
surface of the pattern member 401A of the first layer (a surface in
contact with the metal substrate 400) that is transferred to the
target substrate 410 and the surface of the pattern member 401B of
the second layer are cleaned as described above.
[0148] Then, as shown in FIG. 5E, the upper stage is lowered to
connect the pattern member 401A of the first layer to the pattern
member 401B of the second layer. As shown in FIG. 5F, when the
upper stage is lifted, the pattern member 401B of the second layer
is peeled off from the metal substrate (the first substrate) 400
and transferred to the target substrate 410 side.
[0149] Similarly, for other pattern members, the donor substrate
405 and the target substrate 410 are positioned and repeatedly
connected to each other and separated from each other, so that
plural pattern members respectively corresponding to the sectional
forms of the classifying device are transferred to the target
substrate. When a laminated body transferred onto the target
substrate 410 is detached from the upper stage and the target
substrate 410 is removed, the classifying device may be
obtained.
[0150] In the above-described exemplary embodiment, the donor
substrate is manufactured by using the electro-casting method.
However, the donor substrate may be manufactured by using a
semiconductor process. For instance, a substrate made of an Si
wafer is prepared. A mold releasing layer made of polyimide may be
formed on the substrate by a spin coating method, an AI thin film
as a material forming the classifying device may be formed on the
surface of the mold releasing layer by a sputtering method and the
AI thin film may be patterned by a photolithography method to form
the donor substrate.
Example
[0151] The present exemplary embodiment will be described in more
detail by using an example. However, the present exemplary
embodiment is not limited to the below-described example.
[0152] In this example, the particles are classified by using the
classifying device shown in FIGS. 1 and 2. In the classifying
device shown in FIGS. 1 and 2, the entire lengths of the
classifying passages are respectively set to 150 mm. Further, the
classifying passage is a tubular shaped passage having a circular
section with a diameter of 5 mm. The coarse particle dispersion
liquid discharge port has a circular form with a diameter of 1 mm
and the connecting passage from the coarse particle dispersion
liquid discharge port also has a tubular form having a circular
section with a diameter of 1 mm.
[0153] As the dispersion liquid A, aqueous dispersion liquid (15 wt
%) of spherical particles of polymethyl methacrylate (PMMA)
(produced by Sekisui Chemical Co., Ltd., Techpolymer) is used and
fed at liquid transport speed of 40 ml/h. Reynolds number at this
time is 3 in the laminar flow.
[0154] The particles are classified continuously for three hours. A
classified result at this time is shown in FIG. 6 and FIG. 7. FIG.
6 shows the result obtained by classifying the particles using the
classifying device shown in FIG. 1. FIG. 7 shows the result
obtained by classifying the particles using the classifying device
shown in FIG. 2.
[0155] Now, FIG. 6 and FIG. 7 will be described below.
[0156] In the classifying devices shown in FIG. 1 and FIG. 2, the
particle dispersion liquids discharged from the fine particle
dispersion liquid discharge port and the coarse particle dispersion
liquid discharge port are collected in such a way as described
below. [0157] Dispersion liquid (1) indicates the fine particle
dispersion liquid discharged from the fine particle dispersion
liquid discharge port of the first classifying passage. [0158]
Dispersion liquid (2) indicates the fine particle dispersion liquid
discharged from the fine particle dispersion liquid discharge port
of the second classifying passage. [0159] Dispersion liquid (3)
indicates the fine particle dispersion liquid discharged from the
fine particle dispersion liquid discharge port of the third
classifying passage. [0160] Dispersion liquid (4) indicates the
fine particle dispersion liquid discharged from the fine particle
dispersion liquid discharge port of the fourth classifying passage.
[0161] Dispersion liquid (5) indicates the coarse particle
dispersion liquid (total quantity) discharged from the coarse
particle dispersion liquid discharge port of the fourth classifying
passage.
[0162] A fraction (1) indicated by 1 in the drawing) shown in FIGS.
6 and 7 represents a collection rate of the particles in a first
stage. That is, the collection rate of the first stage is expressed
by a below-described equation in each particle diameter.
Collection rate (first stage) (%)=dispersion liquid (1)/(dispersion
liquid (1)+dispersion liquid (2)+dispersion liquid (3)+dispersion
liquid (4)+dispersion liquid (5))
[0163] Further, a fraction (2) (indicated by 2 in the drawing)
represents a collection rate of the particles in a second stage.
The collection rate of the second stage is expressed by a
below-described equation in each particle diameter.
Collection rate (second stage) (%)=(dispersionliquid (1)+dispersion
liquid (2))/(dispersion liquid (1)+dispersion liquid (2)+dispersion
liquid (3)+dispersion liquid (4)+dispersion liquid (5))
[0164] Similarly, a fraction (3) (indicated by 3 in the drawing)
and a fraction (4) (indicated by 4 in the drawing) respectively
designate collection rates of the particles in a third stage and a
fourth stage. The collection rates of the third stage and the
fourth stage are respectively expressed by below-described
equations in each particle diameter.
Collection rate (third stage) (%)=(dispersion liquid (1)+dispersion
liquid (2)+dispersion liquid (3))/(dispersion liquid (1)+dispersion
liquid (2)+dispersion liquid (3)+dispersion liquid (4)+dispersion
liquid (5))
Collection rate (fourth stage) (%)=(dispersion liquid
(1)+dispersion liquid (2))+dispersion liquid (3)+dispersion liquid
(4)/(dispersion liquid (1)+dispersion liquid (2)+dispersion liquid
(3)+dispersion liquid (4)+dispersion liquid (5))
[0165] As shown in FIG. 6, in the first stage, the collection rate
of the particles having the particle diameter of 5 .mu.m or smaller
is more than 40%. The total collection rate of the first stage to
the second stage is more than 60%. The total collection rate of the
first stage to the third stage is about 95%. The total collection
rate of the first stage to the fourth stage is substantially
100%.
[0166] Further, in the collected fine particle dispersion liquid,
the mixture of the coarse particles (for instance, the particles
having the particle diameter of 15 .mu.m or larger) is not
recognized and a good classifying efficiency is obtained.
[0167] In the example 1, the particle concentration of the
dispersion liquid (1) is 21.7 wt %. The particle concentration of
the dispersion liquid (2) is 14.3 wt %. The particle concentration
of the dispersion liquid (3) is 9.8 wt %. The particle
concentration of the dispersion liquid (4) is 6.9 wt %. Further,
the particle concentration of the dispersion liquid (5) is 22.4 wt
%.
[0168] On the other hand, in the example 2 having the circulating
passages shown in FIG. 2, the particle concentration of the
dispersion liquid (1) is 21.1 wt %. The particle concentration of
the dispersion liquid (2) is 13 wt %. The particle concentration of
the dispersion liquid (3) is 8.5 wt %. The particle concentration
of the dispersion liquid (4) is 5.9 wt %. Further, the particle
concentration of the dispersion liquid (5) is 26.5 wt %. The
results are shown in a below table.
TABLE-US-00001 TABLE 1 Particle Average particle concentration (wt
%) Diameter (.mu.m) Example 1 Example 2 Example 1 Example 2
Particle dispersion 15.0 15.0 9.8 9.8 liquid fed Dispersion liquid
21.7 21.1 9.3 8.9 (1) Dispersion liquid 14.3 13.0 9.5 9.4 (2)
Dispersion liquid 9.8 8.5 9.7 9.6 (3) Dispersion liquid 6.9 5.9 9.9
9.8 (4) Dispersion liquid 22.4 26.5 10.5 10.7 (5)
[0169] FIG. 6 is compared with FIG. 7. When the classifying device
of the example 1 having no circulating passages is used, even if
four-stage processes are carried out, the collection rate of the
particles having the particle diameter of about 5 to 10 .mu.m does
not reach 100%. Further, an absolute value of the inclination of
the collection rate to the particle diameter is decreased. However,
when the classifying device of the example 2 having the circulating
passages is used, the collection rate to the particles having the
particle diameter of about 5 to 10 .mu.m reaches 100%. An
inclination of the collection rate to the particle diameter is
substantially vertical. When the circulating passages are provided
as described above, the particle concentration of the dispersion
liquid is supposed to be restrained from being high and the
classifying efficiency is supposed to be restrained from being
deteriorated due to a force between the particles.
[0170] When the device is set to an angle of 30.degree. under the
conditions of the example 1, the particle concentration of the
dispersion liquid (1) is 31.5 wt %, the particle concentration of
the dispersion liquid (2) is 17.8 wt %, the particle concentration
of the dispersion liquid (3) is 10.3 wt %, and the particle
concentration of the dispersion liquid (4) is 6.0 wt %. Further,
the particle concentration of the dispersion liquid (5) is 9.4 wt
%.
[0171] Average particle diameter of the dispersion liquids are: 9.8
.mu.m in the dispersion liquid (1); 9.7 .mu.m in the dispersion
liquid (2); 9.9 .mu.m in the dispersion liquid (3); 10.1 .mu.m in
the dispersion liquid (4); and 10.5 .mu.m in the dispersion liquid
(5), respectively. When the discharge of coarse powder is
deteriorated, the classifying efficiency is more deteriorated than
that of the example 1.
[0172] The foregoing description of the embodiments of the present
invention has been provided for the purposes of illustration and
description. It is not intended to be exhaustive or to limit the
invention to the precise forms disclosed. Obviously, many
modifications and variations will be apparent to practitioners
skilled in the art. The embodiments were chosen and described in
order to best explain the principles of the invention and its
practical applications, thereby enabling others skilled in the art
to understand the invention for various embodiments and with the
various modifications as are suited to the particular use
contemplated. It is intended that the scope of the invention
defined by the following claims and their equivalents.
* * * * *